Adjuvant Metronomic Chemotherapy After Surgery in pT1-T2 N0 M0 HER2-Positive and ER/PR-Positive Breast Cancer Plus Targeted Therapy, Anti-Hormonal Therapy, and Radiotherapy, with or Without Immunotherapy: A New Operational Proposal

Abstract

Breast cancer is the most common and deadly female-specific malignancy in the world. Four immunohistochemical subtypes are distinguished: luminal A, luminal B, HER2-positive, and triple-negative. In turn, the HER2-positive subtype presents two variants depending on the status of the hormone receptors. The variant that expresses them can benefit from both anti-HER2 and anti-hormonal therapy. Today, MCTP finds application in maintenance therapy after standard of care and in advanced breast cancer when the patient's clinical condition is already seriously compromised by metastatic disease; in this context, it is used as a first-line treatment, in pre-treated subjects, or as a rescue treatment. Here, the use of adjuvant oral MCTP after surgery at an early stage in HER-2 and hormone-positive local breast cancer is proposed, where effective treatment options are available, such as anti-HER2 therapy (e.g., trastuzumab, pertuzumab), anti-hormonal therapy (e.g., tamoxifen, letrozole), radiotherapy, and, in case of strong PD-1 positivity, immunotherapy.

Keywords: antihormonal therapy; breast cancer; estrogen receptor; human epidermal growth factor receptor 2 (HER2); immunotherapy; metronomic chemotherapy; progesterone receptor; sentinel lymph node biopsy; targeted therapy; trastuzumab.

Figure 1

Global incidence and mortality of female tumors throughout 2022: breast cancer ranks first in both incidence and mortality. The number of deaths from breast cancer is slightly higher than new cases of cervical cancer, the second most common female tumor in the world. These data are very illustrative of the socio-health burden linked to breast cancer even today [data source: Globocan].